Just found out my company has under paid my pension for the last 2 years Help

Roadrider007

I have just discovered that the company i work for has not been paying in the minimum 5% into my pension from my wages it was only taking 3% the law changed back in april 2018 and since then they have only taken the 3% agreed amount before it went to 5% which is the amount that they and the government both match.The man in charge is saying the deficit is £886 and the best way to resolve this matter is to up my payment for the next financial year to 9% direct from my wages which they will match taking me back to where i should be in  his words.I asked about lost money i.e the 2% from them government and myself over last two years said covid had wiped off that intrest as markets dropped alot.
I don't really understand how pensions work thought they were like an endowment policy if anyone could help me resolve this matter i would really appreciate you help 
Do i need to seek a pension adviser ? 

xylophone

Speak to TPAS for advice.  0800 011 3797
https://www.pensionsadvisoryservice.org.uk/pension-problems