Unable to pay in cash coins over the counter

I own a new start up business and have a business account with Santander for 7 months. We are profitable and most of our income is with BACS or cheques. Occasionally some of our customers pay by cash including coins.
Today I had an awful experience at the Clapham Junction branch who refused, even after speaking with the manger, to pay in my coins. They said I had to pay in notes at the ATM and go to the Post Office to pay in £6 of coins !!
I pointed out that the Harrow, Clapham Common, Brixton and City of London branches have all allowed me to pay in cash over the counter - usually after the ATM rejected notes which have writing on them.
Their customer service at the retail branches is poor. SMEs like myself do not have time to be messed around like this.
The ability of staff to use common sense is non existent.

I will be changing my account. The prime minister to trying to help small busineses by reducing red tape yet Santander just does not get it