Thank you for the reply guys, I really appreciate the help. I have topped up the transmission fluid and unfortunately this doesn't seem to have helped. I'll put a video on YouTube tomorrow and post the link in this forum if this may be of any help? The transmission itself has 74k on the clock, from reading the car manual it's very close to needing a complete transmission fluid change and filter, I was hoping that this could have just been the issue with some parts being clogged up potentially?

it seems as though the whining noise is coming from the transmission somewhere, it's a hard one to exactly locate as the previous owner has put an after market exhaust on which makes the noise harder to pinpoint. I've tried many car garages today and non have been willing to help, all saying they don't specialise in automatics.. Mercedes flat out refuse to help as well as it's not a Mercedes badge despite it being a Mercedes engine.

Transmission fluid topped up, I'll check the fluid level again to be certain, I don't have the dip stick so I'll try it with cable ties as I saw that someone on here previously has used this method before to measure fluid level?

Thanks again, it's really helpful and appreciated