Nedbank Home Loan Period

I have a homeloan with Nedbank and have been paying it for more than 17 years , I have been paying an extra 900 rand to my bond but each time I ask about the outstanding months I am told its 20 months . In 2022 March I was told I still have 20 months to pay , in 2023 March again I was told still 20 months left and this year now I am told its 22 months left . Its starting to be a **** from Nedbank now.