Got a 54 plate fiesta non abs has had new discs and pads fitted when I picked it up pedal was on the floor, was told needed a new master cyl had one fitted and bled by different garage still same pedal creeps with engine off when started just goes straight to floor! Any help greatly appreciated

 

Master cyls don't just go like that, they will lose pressure first, unless the people doing the pads/discs have caused seal damage by not slackening the bleed nipple when pushing the caliper pistons back in to suit the new thicker pads.
Some cars you need to undo bleed, others you can get away with just pushing the caliper pistons back in.
At the end of the day if the brakes were working perfect and just needed new pads/discs then the damage must have been done by the people that fitted them, in which case they shouldn't have let the car go, as they are liable, or at least should have told you it was un roadworthy with duff brakes.
tabetha