If you've had trouble playing a disc from us, then bring it back, along with your player, and we'll try and work a way around the problem. Sometimes, re-recording it in a different way can help, though the chances are that the solution will be that you'll need a newer player. We don't sell players, so making more money off you isn't the motive, just to identify what the problem really is, and what solutions are possible.
Unfortunately, DVD compatibility between different discs, players, and recorders is rather poor. This is beyond our control, it's the fault of manufacturers who will not abide by the specifications, and the creation of new, and incompatible, standards. I suffer from this, myself, with five different decks with differing abilities at handling some discs (some won't play, some will, some will mess up during fast-forward or rewind operations).
As such, we cannot guarantee that you will be able to play a disc recorded by us, nor can anyone else make such a guarantee. Anybody doing so is being dishonest. But to give you the best chance at being able to play them, I buy the highest quality discs that I can find (currently, discs made by Verbatim work the best with my gear—the decks recognise the discs rapidly, they read and write without noticeable errors, and don't appear to deteriorate). Some other medium priced discs aren't too bad, but they're definitely not as good, and I don't see any value in saving something like fifty cents on disc price at the cost of reliability. And, as you'd expect, just about all cheap media is diabolical (e.g. it takes ages for the deck to figure out what to do with an inserted disc, and often fails completely; writes often fail; they often have really bad reading errors, and lots of them; you find discs that seemed fine one day are useless, later on; etc.).
Having said that, most modestly priced players made in the last couple of years do manage to play a wider variety of discs than older players, or even the expensive models. And players specifically advertising that they support DVD plus (DVD+R) or minus (DVD-R) discs are your best bet.
I like to ask people if they can play “recorded” discs before offering to make a DVD for them, and can lend them a prepared test disc to try out, first. (NB: Recorded discs are not the same as copied/pirated movies. They're a different format, and I don't want to know about people pirating movies)
In short, pressed discs (like movies that you buy or rent), DVD+R, and DVD-R burnt discs are all physically different than each other. And video recordings made onto DVDs are different, again (DVD+VR or DVD-VR). I have a DVD info page that goes into all the gory details about that, for those that are interested.