they offerd you a free brake check
there is nothing to say you have to get the work done by them
thank them for their time and take it elsewhere
£101 for a set of cylinders that will cost them about a tenner is a rip offm unless they already included the cost of labour for fucking up the bleeding and breaking of the bleed nipples into the price
did they remove the drums and then check to see if the seals were leaking on the cylinders?