Right, sorry about the misunderstanding.
You should refer to the agreement originally made with the Company to check that the original agreement was assignable (ie. able to be sold to another company under the terms of the agreement).
If the lease agreement has correctly been sold by the original party and bought by another company each party to the agreement (ie. you and the new company that has purchased the insolvent company's interest in it) would be still be bound to perform their responsibilities under the agreement.
The agreement should refer to each parties' responsibilities and if the new company is not fulfilling a term of the agreement (ie. providing back up) then the agreement may entitle you to terminate it and return the items.
If the agreement does not entitle you to terminate it because of the breach of duty to provide backup then you will nevertheless be able to make a claim under contract law for a breach of contract for any expenses or losses incurred as a result of the breach (ie. the expense of paying for alternative backup)
After checking the agreement you should write to the other party confirming the breach, detail the costs incurred as a result of the breach and claim the sum from them. Ask to be paid within 7days failing which a claim will be made in the small claims court . You will be able to this yourself online though http://www.moneyclaim.gov.uk/.
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