Firstly, I'm afraid you are certainly not going to obtain a marriage visa for your fiance before the end of September so, regrettably, your plans to marry here in September are not feasible.
You have got to focus on persuading the UKBA that she does intend to return to Ghana once you are married. If you have leave to appeal then do so. If not then you will have to make a further application. The evidence you can produce to show that she intends to return would be things like evidence of continuing employment (eg. employment contract, statements from her employers), continuing studies if applicable, evidence of continuing accommodation that she is to return to, statements from you both to the effect of return, evidence of your plans/practical arrangements for residing in Ghana once you are married.
If you cannot persuade the UKBA then the easiest thing to do is for you to return to Ghana to marry there and then apply as appropriate for her visits here with you when you are working.
Two of the applications forms that were submitted were not appropriate for the application and they were probably refused on that basis.
Sorry it could not be better news, but until you are able to persuade the UKBA that she will return to Ghana then the situation will remain as it is now.
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