Just read your entire thread. I m sad to hear about your issue.
Got my YBR 125G nearly 3 weeks ago. Done 1600 so far. First Oil change at 500km LM 10W40. Second at 1000Km by Yamaha Oil ZIC 10W40 as Yamalube was not available. Issues that i m facing are
1. Fuel gauge gives incorrect reading
2. Gear stucks few times every day
3. Top speed is 100km/h
Despite all these issues, i absolutely love driving my bike. I try to be as careful as possible. My daily mileage is 70Km and average speed is 60-70 km/h. I m not in favor of going to any mechanic as of now. Most threads on 125G will tell u ppl r facing missing and speed issues and in t he same threads those ppl had them resolved after 3000 Km or the second servicing. I tell u that this machine was performing super after the first oil change at 500 LM 10w40 with no tune up and after the first tune up at 1000, performance(pickup n speed) has significantly decreased. I m not going to feel it neither i m going to ask the mechanics to fix it coz i know every mechanic will tune it as per his own skill set n knowledge. I m waiting for 3000Km milestone and after that any performance issues will be dealt by DIY way
Don't even think of selling your Yamaha. Its a world class company. Just coz some idiot messed up your machine settings does not mean its a piece of junk. Customer care of Yamaha will improve with time and so does the skill of mechanics. til that time hang in there and this forum and internet are your tech buddies.
Have faith in Allah and don't regret your decision :)