Similar with me, never spoke to stepchange but did the credit card companies, defaulted and paid what I could afford each month, they would want an annual review to check if I could pay more but I’d usually swerve that by being too busy to speak on the phone and as long as I kept up with the DD they were happy. As that was now interest free and cheap I could pay off other stuff.
Despite the default it didn’t seem to affect my credit rating too much as once things got better I managed to remortgage which then saved me even more money.