Efird Dodge Ripped me off for $115 dollars on something they "diagnosed" wrong and did not fix Florence sc South Carolina

Brought care in on 5/23/18 to fix two things. One was an airbag light that was on. They charged $115 diagnostic fee and the light was off for one hour and back on. I called them the next morning and told them (5-24-18). They found a lose circuit supposedly. Brought it in today (6-18-18) (after my vacation) and they want to charge me over $600 because now it was something else a “clock spring” under my dash. I told them do not fix it – too much money and I want my $115 back for wrong diagnosis and not fixing it in the first place. They refused.