If it is due to mortgage arrears and they are in the last 3 months you will be unable to refinance unless there is a legitimate, easily explainable reason and there is no other history of arrears. If there are missed payments on the mortgage within 6-12 months there are lenders out there who will consider lending. If the bad credit is a result of missed payments on other type of credit again depending on when the arrears happened and how much the arrears amount to, they can be ignored. If one is looking to remortgage as they are at eviction stage, you might be able to access alternative finance options such as bridging loans. It best to contact a mortgage broker
who has a range of lender on their panel and will be able to find you a lender based on your level of adverse.