Sounds like the problem I have with my 5 door. I had it scanned and the results were that one rear locking control module thing was showing implausible and the other was showing intermittent. Basically one is knackered and the other is nearly knackered. I am having both replaced. This seems to be a known if not too common problem/ issue with the mk5. Have a bash with the search function and you will find a few threads dealing with this problem. My advice is to get your car scanned to see if the problem is one of these pesky control module thingies. Good luck