I'm wondering if the garage cleaned the new discs before fitment?? They have a coated film which needs to be removed with a generous amount of brake cleaner.
If not, it would explain your description and can be dangerous, as its basically a fine coating of grease, for want of a better description.
Get some brake cleaner spray and give them a go over and recheck.
Was the brake fluid changed?? Needs doing every two years.. Check your hoses and connections etc
Last edited by PJ3074; 23-05-16 at 20:21.