BT...TV box

I have a problem with my provided BTtv box , some recordings and indeed some veiwed channels have lots of interference up to 60 minutes. I contacted BT  and explained the problem ( which took about 1/2 hour ) and after retuning swopping cables it was agreed an engineer would call and access to situation. The engineer called two days later and after a lot of testing finally agreed that the problem was with the box , and the aerial was OK. He also  left a report stating this.the next evening BT called to ask for the engineers findings my wife read out the report  to BT but they then decided as the engineer was not an employee of BT then we should try re-scanning etc etc  which we refused to do ( bearing in mind they sent the guy ) to cut a very long story short anothr BT engineer is now appointed. I am not happy with this to say the least as we now have to await another report. I tried to find my contract finish date as I feel I now want to change providers because in my opinion BT do not look after their present customers. Has anyone else had problems with BT and secondly does anyone know how to find your contract details and expiry date ? ?