Contax RX repair in the UK contaxrepairs.com still open?

HI all just wanted to know of any where in the UK that can fix a Contax RX.

I recently bought a Contax RX from japan the item was sold as in mint condition but after shooting a couple of rolls of film I noticed that some of the negatives I developed had something obscuring the lower half of the frame. In some pictures what ever it is is clear and you make out the shape etc

I then removed the lens and fired the shutter and I noticed that occasionally the mirror seem to move up get caught then fully retract/fold up. I read about mirror slip and contax cameras but this seems to only occur with the lens attached.

Have any of you heard of this issue before ? Or have any ideas if it is something that can be  fixed?

Thanks for any help