They are having you over IMHO - get a second opinion mate and we never or very rarely have to buy new stuff as someone on here's nearly always got bits lieing around to help or breaking one ....
As for the belts - run it till it really needs them would be my advice .... a new engine can be yours IF they go for less than the cost of getting them done.
__________________
------------------------------
------------------------------
__________________
------------------------------
------------------------------
|