I'd give them a second chance.
Hi Mario,
I'd give them a second chance. I'd write them an E-mail before ( or use snail mail ) stating that you are unhappy with the service they performed & that the watch is now performing "OUTSIDE" of COSC limits.
I'd also get them to agree that the watch will be returned performing WITHIN the limits & if it doesn't you will expect the watch corrected at their cost ( incl all postage expenses ). & sinbce the problem has occured WITHIN the guarantee period I would also state that I expect them to correct the problem free of charge, even if it is not finished to your staisfaction before the guarantee expires.
If you send them an E-mail, you might want to consider copying aftersales--at---omega.com on your E-mail. They are usually pretty good at looking after customers.
I'm afraid that I have no experience of US Omega centres. I do have to say though that I rarely read much positive about them.
Finally I didn't understand you comment...
I would wind it ( 50 times) on friday, just before the weekend, then my watch would stop overnight on thursday.....
It runs for 6 days ?