Non-numerical characters in bank Account Numbers

Would it be possible to allow letters in bank Account Numbers?

My issue is that my bank, LCL, like many banks in France, have letters in the account number. E.G. 123456A. This means, when I try to import transactions into FreeAgent, I get the error :
"There is no bank account which matches the data in your statement"

For now, as a workaround I can enter the bank A/C without the letter and modify the corresponding field in the tx import files before I import.

Phil