Planet Payments is the 3rd party company that Peach uses to facilitate Multi-Currency transactions.

If you are making use of multi-currency functionality, take note of restriction on the transaction ID length - which can be set to a maximum of 25 characters. 

A transaction with a transaction ID longer than 25 characters will fail with the following error "transaction declined (format error) (800.100.156)"

Please see below an example of the above-mentioned` error:

Example of a POST Request that will FAIL:

This request below has more than 25 characters, and will therefore fail as above: 

The merchantTransactionId should be 25 characters or less