[Q] Problems buying Navigon Europe on Marketplace - How to Solve???

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http://forum.xda-developers.com – I'm trying to buy Navigon Europe from Marketplace but it keeps saying my payment details may be incorrect (although they're not). I've checked with my bank and the requests to buy the app have not arrived with them. I've chatted online with Microsoft support but they say the problem may be with Navigon themselves and that they will escalate my issue but I haven't had any feedback from them. I have bought apps successfully in the past with the same card (a Visa Debit). In desperation I have tried various cards (debit and credit, all OK) and setting up a new Live account but to no av (HowTos)