failing to convert pdf to word or excel document

Hi,

I have just signed up. I have some pdf's from work which are about 90mb. I have tried converting three pdfs to word documents and each time it fails to convert.

It doesn't give any more information. Is there anything else I can try? The help seems quite limited. I signed up to convert my work pdf's to word & if it can't be done then I will ask for a refund.

Cheers