IFB Industries — how can a company refuse to supply spares

Address:

Ifb akkayyapalem visakhapatnam, 530041

When I asked for the belt to be replaced the visakhapatnam IFB service center at Akkayyapalem.They refused to sell the spare part and said that they would come for a visit if I agree to pay Rs600 as service charge plus cost of spare part namely (Belt). how can a company refuse to supply spares if i can fix it by myself