Escalation - U.K. Visitor visa.

[Jgorf]

I need your advise please . My sister applied for a uk visitor's visa following my invitation. She'd did biometrics in June (Nigeria) . ECA called my over a month ago to enquirer about the application. After the all was told we will get a response in about 1 week.

Till date , no information from UKVI. I have called the help line a few times with each call costing over £10. They aren't always as helpful as they really don't hold much info.

Does anyone know how I can escalate this please. Does it make sense contacting my mp considering the applicant isn't a British citizen but she is my sister and I invited her!. He application is just over 50 working days .

Many thanks