Promises promises... 5 months down the line and I am still left having to follow up

Overall my experience was pleasant until... I informed them, with 30 day notice, of my bank account details changing. They failed to update my account and then proceeded to charge me a late fee when the debit order failed. This happened in May 2017. It is now September and I have been following up every month, from USA. After promises and promises, from Schalk Wurth, that the late fee will be credited to my account, and eventually he promised to pay it back into my bank account, nothing has been done to date. Customer Service? What Customer Service???