Unreasonable requests and unfair terms and conditions

I have come across this company recently when I was asked to stand guarantee for my granddaughter's tenancy. They started off by asking copies of a host of documents amongst them my driving licence, P60, and mortgage statement, which would have been a god-sent to any identity fraudster. Upon my protestations, after several emails, they agreed to carry out a credit check instead, which I had suggested in the first instance. They also claimed that the documents were requested by the landlord, when they were clearly only following their own procedures. However, concerning the guarantor agreement, this obviously was an off-the peg job. In no way was it acknowledged that this was a joint tenancy and that my liability should have been restricted accordingly. Also, in case of default, signing the agreement would have laid me open not only to paying the rent due, but any charges, expenses and compensation the landlord (or his agent?) might think fit to request. There was no fee structure or arbitration procedure specified for this eventuality, something which even ebay and Amazon provide as a matter of course for far simpler transactions. In addition, one of the clauses in the agreement was in perfect legalese , so much so that it appeared to be self-contradictory. Regrettably, I had to decline acting as guarantor, although I had stood guarantee for my children and grandchildren several times in the past without any problems at all. A totally unprofessional job, with the only positive aspect being the speed of response to my emails and the willingness to pull back from their initial unreasonable demands concerning the provision of documents. However, the result that my granddaughter may have difficulties in securing the tenancy.