Right, which says that Adelaide away games are not going to be a priority in a hurry.
They have no responsibility to you at all unless you signed a contract that specified a minimum number of away 36ers games. Or unless the NBL have a contract with them that demands that (doubt it would ensure equality, maybe a minimum 1-2 games per club if anything).
Without a contract specifying as such, a company is not legally obliged to provide particulars - yes, they will cater to subscribers where it benefits them as a company, but this will favour the masses which means (a) sports other than basketball and (b) cities with greater populations. That's not a responsibility to you - that's strategy to get the best bang for the buck.
Vote with your wallet when your subscription ends if it matters enough to you, or if you don't watch enough other TV (I don't really watch FTA as it is, so Fox would be a waste for me). Or write a letter now saying that you won't continue after this contract unless the situation improves, or would appreciate more Adelaide away games, and then cross your fingers. Depends on why you have Fox and what you get out of it, I guess.
I think that with solid bargaining you can get a good deal without locking into two years as well - you just have to be persistent in dealing with them.
You said: "you shouldn't have to put up with a service that is not meeting your needs" - why's that? As I mentioned, you signed a 24 month contract and nowhere was it specified that you would receive x away games per season. If they cover more Sydney road games at the expense of Adelaide road games, they'll could get a better return due to the larger population of Sydney - they're not going to care because EC in Adelaide thought she'd get more games of her team on the road - that's just how it works.
If all you want Fox for is occasional Adelaide road games, catching them at the pub is the best deal, IMO.