Did you try DrByte's tip:

If you're having a "db user exceeded" problem, then your hosting account is slightly underpowered for your site. The *best* solution is to switch to a hosting company that doesn't impose unrealistically low restrictions on your account.
That is the only solution that makes sense. Now you have this problem but once this one is solved you will get other problems like a slow site etc. all because the hosting is not right.