If you don't want to rely on budget mobile contracts the rest of your life, it is important to get your credit score back up. Doing this will take time, but with some simple steps you can get yourself headed in the right direction.
The first thing to do is to check your current credit history. Sometimes these agencies make mistakes, and so making sure your report is accurate is the best first step. You can contact any credit reporting agency and they will provide you with the information you need. If you find any discrepancies, inform the credit agency right away so that they can fix them. Once you have an accurate credit rating, you can begin to repair it if need be. Below are some simple tips to get it back up where you want it.
The best advice is to start small and work your way back up. Apply for simple contracts and credits you think you can get, and then just make sure you pay it back each month. By showing that you are responsible with your money, your credit score will slowly start to reflect that over time.