Smart Bank PPI - VAT on commission

[Greyprincess]

Hi, would appreciate some advice please. I’ve received an invoice from SB. I couldn’t work out the commission charge and was told that it includes VAT ( they quoted 25% + 5%= 30% when queried), they then charged a further 20% VAT. All I can see is their terms and conditions is that they charge 25% commission on any settlements plus VAT. Thank you.