Need To Write Off Proceeds Against Exports

Dear experts, In 2018, I'd lent my name and house address to my acquaintance in good faith to ship a consignment of mixed vegetables. They were exported to UAE and reached in poor condition and hence the buyer refused to make payment of the goods. I was not aware of the situation until 2020 I received a notice from bank saying that the documents need to be submitted and explanation needs to be given why payment didn't come. I met with bank manager but he is saying get email correspondence from buyer stating they will not make payment for reason of poor quality. It is a partnership account and other 2 partners (my acquaintances) are not out of touch I can't find any way to contact the and the manager says please get email or written confirmation from those partners saying " I'm authorizing XYZ to proceed with writeoff of the said export". I'm unable to get in contact with anyone, what is the legal way out in this.