I know this originally started out regarding front parking sensors, but this seems an interesting alternative as a rear parking sensor:

Meta Reversing Sensors

I have bought a pair of these specifically for the front. I haven't had the time to fit them yet but there could be a problem with the front bumper being slightly V shaped. If I succeed I'll let yo know.

i find my front and rears very handy. not sure id order the fronts if i was buying new but i definately use them, sometimes i turn them on when going forwards into parking spaces. better to be safe than sorry.

The car has been to the dealers again, with them saying that the paint is the problem. Pity they don't check their own desktop info. for the correct way to paint them. As they didn't paint them, you would think that they would have given me the masking rings and info. so that I could get them done! If this is the normal Skoda level of service, then I'm regretting changing from Toyota. Not 100% perfect, but a 100 times better than this lot!

Well, after all these months the car has been back to the dealers, who think it might be paint on the sensors. Having read the threads associated with this post, I realise that the paint should not enter the sensor grooves, hence the masking rings! Unfortunately the dealer failed to point this out to me, did not supply the rings, and never asked me if I wanted them painting in the first place! I asked him if he thought that I would really want to have a car with four black discs sitting in a cappuccino coloured bumper. The level of service I have received during this protracted problem has been appalling. I have told the dealer as much, but they seem to think that me, the customer, is to blame. I have also contacted Skoda UK, who just negated any responsibility by saying that the dealers were independent, and it's only them I should deal with. Obviously they don't consider the damage caused to their brand by bad dealer experiences anything to worry about I thought these type of dealers disappeared years ago, obviously not in this case. I'll think seriously about using them again.