Incorrect Visa Expiry Date

I have recently received my BRP for Tier 2 general however the expiry date is before the contract end date.

This was my third extension of the tier 2 Visa ( I am on a temporary contract at the moment so need to apply for a new visa every year)

The previous two visas have been full length of the contract plus 14 extra days. My yearly contract runs from 1st September to 31st August every year and the last two visa i have got have expiry date of 14th September. However this time the expiry date was 14 August, which i believe is an error.

I have written to BRP error team however they responded that they cannot change the expiry date and I f I want to dispute the expiry date i should contact the case worker. I don't know how to do this.

Any advise with the above matter is highly appreciated.