expected customer service from a VAG specialist garage from a recent repair

All fellow Skoda and VAG car owners: last week I took my much loved Skoda Octavia VRS MK2 2.0 petrol owned from new into a local VW specialist garage for a water pump change due to a coolant leak. Picked up the car and drove it back on a short drive and parked her up on the drive. yesterday time to go into the office 80 miles away and set on my way, soon into the trip I noticed the car running a bit doggy and noticed the gear change notifier wasn't working as normal not indicating when to up gear or it took like 5000 rpm before it kicked in, i also noticed a slight power difference or car behaviour and the fuel mpg was not as good. Anyway I got to work and parked up until lunch time so I can have a look under the bonnet. 

Lunch time and time to have a look - I opened the bonnet to notice 2 things straight away 1, the air intake top box cover was off and fell down the gap in-front of the battery housing so there was a huge open gap. 2, I noticed a jubilee clip tightened around the moulded neck of the vacuum sensor at the front of the engine which wasn't there before. So some history - I changed that sensor 4 years ago with another sensor from a VW Tougan yes just the sensor rather than paying hundreds of pounds changing the whole assembly and having to remove the manifold. So I removed the old sensor by unplugging and cutting the hose then joining the new sensor onto the existing hose and coupled with a plastic insert and covering with adhesive lined black heatshrink. It looked smart and done the job with a local fix, the hoses were sealed with an insert to prevent collapse. The new sensor is a slightly different shape with a moulded shoulder taper coming away from the sensor which my heatshrink covered. I did put a jubilee clip over the hose loose just incase the heatshrink didn't do the trick but it did but I never removed it. What the technician decided to do was fit the jubilee clip over the shouldered taper and tighten it up as much they could. When I removed the clip I instantly noticed a hole/damage on my heatshrink but unsure how deep it goes, the hole was created by the sharp inner part digging in when tightening. I was concerned over 2 things 1, what is in that moulded taper area, is there anything delicate which could be crushed inside, is it an integral part of the sensor and 2, has it pierced a hole through the hose aswell as the heatshrink. 

Grab the Rhino tape and taped on the air intake cover and grabbed some self amalgamating tape and wrapped around the area with the hole. Time to drive home 80 miles - what a contrast, she drove like a dream again, gears notifier back as normal happy days but annoyed about the 2 point above. 

Today my son had his Audi A3 2.0 TDI 8P booked into the same garage for a Glow plug change and I was dropping him off - time for to mention what I have found.... well I was not expecting the response I got, the person involved was the workshop manager and from the off they was on the defensive. All I wanted to do was bring them to the attention of what I found, straight away it was yes we was doing you a favour fitting it back on - it was a bodge job I had done - the car is 13 years old 145k on the clock and past it - they refused to put it on the system in case something happens in the near future. They said I was being unreasonable but I hadn't asked for anything - they said to do the job properly is 4 hours labour plus parts that's why I done a bodge, well yes but it was working! then he said so why didn't you change your own water pump as I replied because I can't and you know I can't because it's the most complicated waterpump location and access I have ever seen as they replied yeah I know tough gig. They thought I was just a dumb ass who know's nothing but I know my way around this car and done some pretty tough repairs.. ABS module being one. 

They did offer to then do a local hose repair with 2 jubilee clips which I said no thanks I can do that myself - all in all a tad disappointing experience, I am nearly 50 years old and I have never experience such aggression, poor attitude from a customer facing employee ever, my teenage Son who was in attendance was left shocked by the experience. I just don't know what to do for the best, comments welcome please on what best to do if anything...

Thanks for reading