There is no simple answer to problems caused by bad councillors. If the issue is particularly serious, you can raise it with the Monitoring Officer, who is usually the senior legal officer of the district council. But the supervision regime for local councils is pretty toothless, so do not expect too much.
Otherwise, the short term answer is publicity. Write to the press, or, better still, write regular reports on council meetings for the local press. Talk to other electors, maybe even circulate a newsletter about local affairs including comments on the local council.
Longer term, councillors have to be elected every four years. Stand as a candidate. You will find it hard to make an impact on your own, so aim to recruit a group of people who are willing to stand and will make more conscientious councillors. Most local councils do not require a very large amount of work from their councillors, and a good council is a valuable part of local life. But a good council does depend on lively local democracy and citizen participation!