Fly sheets take the brunt of UV exposure, therefore the brunt of UV degradation....which is probably why your flysheet ripped. If the fabric is weak, no amount of repair is going to save it because it'll merely rip again promptly, probably during the next wind, rain and snow event.
This can happen after one long season's use in the arctic or at high altitude if your tent stays up day after day, so it's a real issue after steady use for several seasons, particularly if you've spent time in mountains or the subarctic.
If you're lucky the fly still has enough life left in it for repairs to hold, but I'd be dubious and prepare to buy a new tent. Since repairs tend to be expensive, and in light of the fact that they will probably not last long, you might think about doing them yourself instead of hiring out. This can mean accessing the proper material and a sewing machine, or it can involve some duct tape and take five minutes after breakfast. Either way, you'll want to use something waterproof and seamseal any needle penetrations thoroughly.
If you can't spot UV degradation yourself, find a reputable repair shop and, if they say it's not worth bothering, believe them.