Bad service

I booked with intercape bus 18th april and then they send voucher then I spoke with one of the consulted and told her that will book for 11th and she said tget will start on the 10th and now I want to change my bus ticket for tomorw to go back home now they not getting back to me and I have the ticket and they also say no vouchers will be used for this period of 2nd till 7th and they dont respond and their customer service uts poor I need an assistance