As the old number has been disconnected, I cannot see that we will find the new one on the internet. However, perhaps we could have some more information.
Is this the number of one of the branches, or is it a number that goes through to their offices or switchboard. If it is the latter, it may will be 1 of many with the same prefix. It may be worth trying numbers after 200, ie. 01782575201, 01782575202 and so on. You could even try numbers before 200.
Let us know if you find anything, and add it to the database if it works.