2004 Ford Fiesta transmission malfunction

I have had my car for 3 years and use it as a daily driver not once have I had an issue I'm the second person to own the car after it being a mobility car with a fully service history but for the first time since owning it last week I started getting a high pitched noise followed by a warning message "transmission malfunction" following by my car going into some sort of limp mode but 2 seconds later regaining full power and being fine. Because its an older car there's no error codes just a message telling me to check the manual but when I check the manual there's tons of stuff that can cause this I was just wondering if anyone else has had this issue i am taking it to have a fully diagnostic test next week but after doing my research it could cost anything from £350 including labour to £1350 i don't want to go in twiddling my thumbs just don't want to be fleeced out of money.

I know what your all thinking and trust me if I didn't have 13 months left on a finance agreement if scarp it but the finance company are refusing to let me scarp it as its still an "asset" to them

Any help would be great

Mike

Merseyside