The UKBA can be quite difficult with visitors visas I'm afriad.
The eligibility criteria for a visitor's visa is as follows(as I am sure you are aware0, is that you need to show that:-
- Youwant to visit the UK for no more than six months;
- You intend to leave the UK at the end of your visit;
- You have enough money to support yourself during your stay in the UK without working or needing help from public funds
She has to try and show them that she has continuing obligations in the Thailand which will continue after her visit and therefore convince them that she are not a risk of overstay. Things like a letter from her employer stating she has a job (if she does) and are expected to return to continue that job, evidence of continuing accommodation (eg. tenancy agreement of evidence of ownership of a property, bank statements showing the money he has available to her. They should be attached as supporting documentation.
You should assist the application you by going to a local solicitor to draft a sponsorship declaration in which you state the terms of his visit, that she is to return at the end of it, that if you are in a relationship with her then you both know she must leave at the end of the visit because it would harm the chances of any future application made to secure leave to remain, that you shall accommodate her and half pay the costs of any unforeseen expenses that should occur during his stay so that neither of you will need to access public funds. You will have to submit bank statements showing the money you have available for this purpose.
This should cost around £50+vat and you can find immigration solicitors via:-
If the bank statements are the only reason for the refusal you might consider writing to them, attaching original bank statements and asking for a reconsideration but it may be quicker for her to submit a fresh application.
If this is useful please kindly click accept so that I may be rewarded for my time. You will be free to ask follow up questions.