DWP says it has no record of tribunal letters

I applied to the tribunal in early march and received letter from them to say that they had received my appeal on 13/03/2017 and were writing to DWP for a response. After 6 weeks I contacted DWP to ask about my package not being sent and they claimed to have no record of any messages/ letter from tribunal. I contacted tribunal on the same day and was told that the tribunal had sent out a second letter that very day asking the DWP to respond. After a further 2 week wait I contacted DWP yesterday just to gee them up a bit and was told once again that there has been no communication from tribunal and that they would look into it. This has now been two months and the process hasn't even begun. If I hadn't submitted my paperwork within 28 days then I would have been penalised. Has anyone else had this problem?

Thanks for your reply Gordon. I contacted DWP with regard my not receiving package of notes i.e. Medical assessment etc as I was of the understanding it was their responsibility and not TS. Also if the Tribunal goes ahead anyway and I have not received package surely I am then at a disadvantage due to not having all the facts with which to present my case and rebutt the assessment findings.