How the SLA works and how to take appropriate action, when a support case is not resolved

Hi

Our organisation uses a finance software. For this software to work successfully, there is software A, which is a web based and links to another software that is on a hosted platform.
Basically we export a budget from a Software A and the budget gets successfully exported to a local PC and again using software B we have to import the exported budget, when we import we get an error message which says “The imported file is not a valid import file”.
When I escalated this to Software A support, I was told that software B is not setup properly to receive the imported file.
And again when I contacted Software B support, I was told it’s nothing to do anything with them and they say it is the problem with software A and they say it is not exporting properly.
In this situation I have been caught between and both are blaming each other. We pay lot of money for the support for both the software vendors.
It is a week now and I want to take this serious as this case is not sorted still. I want to look at the SLAs and appropriate action.
Your suggestions much appreciated.
Thanks