Receiving 1 payment made up of 3 currencies

Hi there! 

So one of the online B2B marketplaces I sell through sells to the US, EUR and UK. 

They invoice me in the correct currency for each of the areas so I set up separate customer accounts in QB to allow for this. However, I have received a payment made up of invoices of GBP, EUR and USD. 

How do I start allocating this payment to the 3 different customer accounts and in 3 different currencies?

Oh and they also take commission which is also set to the currency for the Country of the customer.

For example:

One order for UK £300 minus £25+VAT fee

Second order for US $289 minus $30(NO VAT) fee

Third order for EUR 155EUR minus 15EUR (NO VAT) fee 

All paid in one payment!!

I doesn't help that they do not acknowledge what the exchange rate for each of the currencies is on the day of payment!

Please help!