Asked to pay for two more years of IHS

I have recently submitted my application to switch from tier 4 to tier 2 and my biometrics have been taken. I paid for one year of IHS as I have a one-year employment contract with my employer.
Unfortunately, I just realised that my employer gave me a certificate of sponsorship for 3 years. Now UKVI emailed me to pay for 2 more years of IHS. After talking to my employer HR, a sponsorship note was added on the CoS stating that the employment contract is only 1 year and they ask me to notify UKVI about this change.
I tried to call the UKVI number, but they are terribly unhelpful and suggest me to email back the no-reply email (that notify me to pay for 2 more years of IHS). I haven't heard back from UKVI since. Is there any more direct way to communicate to UKVI about my case?