Octavia 2 RS door control unit

We have a 2010 VRS (face-lift) driven for the past 2 years by my wife.

During the past few weeks, she's noticing that the remote fob is increasingly struggling opening the driver side of the door. Sometimes it will open on the first go and other times, she tells me, she's had to enter (or even exit) the car, using the passenger side. The later scenario is even scarier! Car was due a major service so asked the dealership to have a look.  They tried a lock from another Octavia we were told and the problem was there. Wiring seems to be OK to. They are convinced, they need to replace the door control unit. Was given a steep price of 350 Euro for supply and fit. Prices on eBay seem much cheaper

Do you think the door control unit is responsible for the said error?