Fuel senders... I actually had this same issue last winter & brought it in for service & of course then it didn't happen any more...the problem randomly went away.

 

I took it to the dealer and they replaced the fuel sending unit (left) and after that i filled up gas and this time it shows till "F".

Is that fine or if the tank if full should it not go above F as it used to go above F before i had the problem

 

Mine always went above the full until the shutter valve problem started then it gradually would take and show less until I could get no more than 3/4 of a tankful.
No problems since the valve was replaced. It fills above the full mark again.
I would say if it gets worse go back and have them do the TSB for the shutter valve.

 

I'll keep a check on that

BTW i had specifically instructed them not to wash the car and they washed and when appologised and said that they can do a free wax on the car -- should i take the free wax

 

LOL...they washed my car once and the service manager phoned me up let me know I could pick up my car and were apologizing big time and stressed to make sure I check it out and they would fix anything up if there was a problem. There was no problem. Try to get a free oil change instead of the wax job. I wouldn't let them wax mine.