Holiday refund using Section 75 and or chargeback

Four of us booked and paid for a weeks cruise with Cruise and Maritime. We refused vouchers and were told that a full refund was to be paid out on July 31st.
Well.... they went into administration about 4 days before.
As leading passenger I had paid the whole holiday from a mixture of my credit card for the deposit and debit card direct to the company, not through a third party booking site or travel agents. I sent all the details including conversations by email to both.
The credit card has acknowledged (when pushed) that they received all the paperwork. Nothing from Barclays for the chargeback claim.
Has anyone else out there ever had dealings with a scenario like this? How long before I get some sort of response? Is there any legal time frame?
We have lost in the region of £4,500 between us!