If we can get a statement from ex-LL, what form should this take so that it is legally valid? Should we get a witness, or do we need to involve a lawyer?

Don't have a scanner, sorry. In any case the tenancy document itself is not very informative - the agreement between the landlady and her tenants was verbal (yes I know). The CAB tell us though that once the tenancy agreement runs out and changes to a rolling monthly one, it is deemed to continue in the manner in which it was run in practice. Therefore, the terms on which the landlady was actually running the contract hold, and we do have some evidence in that regard (though currently not as much as we would like). Meanwhile, letting agent has keys and can therefore let bailiffs in peaceabl

My partner's house was recently sold by his landlady to a letting agency. The letting agent gave notcie that he was putting up the rent considerably, so my partner gave notice that he was leaving the property before that happens. Since then, the letting agent has sent letters claiming that my partner owes him upward of £400 in utility bills and council tax. The agreement with the previous landlady was that rent covered water and council tax, and gas and electric are paid through meters in the house. My partner has refused to pay, and the letting agent is now threatening bailiff act