Deducting 2 decoders payment for 4 months

We ordered the new explorer. First we struggle for them to deliver the explorer. Then they deliver and a wee k after they deliver another explorer decoder. My husband phoned them to come and pick up the second one. We installed the one and waited for them to collect the other one. The courier service came to pick it up ago. After months of struggle. Now they deduct 2 decoders payments every month. My husband spoke to them and the lady we spoke to said she can see all the notes and nothing has been done. She will fix it. Nothing yet now they say we are in arrears. Still nothing done regarding this problem.