Money Transfer to UK

I bought a holiday apartment in Goa some years ago. I had an NRI account. The bank then changed it to an NRO savings account.
I sold it three years ago and the money was paid into this account.
I wish to transfer this money to my UK account.
My bank (Axis) said I need proof of the purchase money coming from UK, and they would sort it.
However, the bank has done nothing for over three years even though I have sent them all the proof they need many times and now ignore my e-mails.
I have a visa and PAN card.
How can I transfer my money?