Upvote:2
should I provide the letter or not?
There is nothing to be gained by including statements such as "I have no intention to over stay or settle". By applying for a visitor visa, you have already communicated that.
I would only include things in additional attachments if those matters are not already covered elsewhere in the application form. You need to balance providing full information with making your application clear and easy to assess.
My father told me it's too much blabla and will complicate things.
Advice to listen to your father is probably more often right than wrong. In this case I agree with your father.
["]why is your father paying for your trip?["] Should I say because I'm a student or give them a more detailed answer?
Since it is not the case that all fathers planetwide give all their offspring free solo vacations to places like the UK during their student years, you probably do need to explain why your father is being so generous. Being a student is usually not by itself sufficient reason for parents to pay for expensive vacations.
the reason [for] the refusal was that [... I] had no ties to my country
You also need to address this in your subsequent application.
I applied twice for a UK visa and both [applications] were refused
If your read about similar cases here, you will see that the usual advice is that you are approaching a situation where you will need professional help from a UK registered lawyer specialising in visa applications.
I would take extreme care over every part of the application.