Hi...servicing will unfortunately cost you closer to $200 + shipping. If you get servicing on an a7750 for the $100 mark it generally means is a dip and dunk servicing and not a complete disassembly, cleaning, proper oiling and reassembly. Servicing generally will take at least 3hrs for somebody doing a REALLY fast job and a lot of investment in equipment and experience...hence the price.
The A7750's (seconds at 12 included) are reliable but need to be serviced within the 9-12 month mark to maintain being reliable. They are dirty and dry (no oiling) when they stick the movements in...so cleaning and proper oiling is required. Some will have movements that last 3x this unserviced...others less than this. For RELIABLE service, a complete breakdown, cleaning and oiling should be done.
There aren't that many people that can service chrono movements relative to how many call themselves watch repairers. There aren't that many people who can reliably repair ASIAN chrono movements...that's the difficulty. I know of more who claimed they could, botched the movement and ruined a watch than actually understand the idiosyncracies of the A7750.
IF serviced an A7750 (seconds at 6 EXCLUDED) and maintained properly, will last just as long as a genuine. Remember...a genuine needs to be serviced within 5 years...and every 5 years. The Asian just needs to be serviced 4 years sooner...otherwise you start wearing parts down because they are running dry metal on metal.
Stay away from Michael Allen watchmaker though!! There are couple folks in EU...don't know of anybody in France. Francisco, Cortebert and a couple others are folks you might try PM'ing. Or, there's a guy in Spain who is supposed to be really good as well...I've never used either...but judging by the posts on this forum, you can decide for yourself.
Good luck.