HDFC Bank — ISA not working

Address:

B-149 Sector 14 Noida, Distt. Gautam Budh Nagar

My ISA account gives me a message while trying to purchase mutual funds. It says the amount entered is not in the right multiples. My kyc is ok and I am certainly trying to buy the funds which I am allowed to buy as a Canadian. I have tried entering different fund houses and funds but the same message appears. My email is [protected]@yahoo.com and I talked with hdfc bank help desk as well as mutual fund department. They just keep giving me each other's phone numbers and I have no option but to shunt and talk to one and then the other only to hear they cannot help me.
Please resolve

Jyoti Dahiya
Imperia customer