Poor Service and overcharge

I booked a flight online with Travelstart for my colleague. I had to make some changes to the ticket as my colleague's itinerary changed. I tried calling the call center many times and waited for more than 10 minutes at a time without any answer. I then emailed the urgent email address listed on the website and I did not get urgent feedback. I then went into the airline offices to make a change and I found that the booking was completely different to the ticket that was issued. I paid an extra $50 for a re-bookable flight when I booked online and the airline still charged me an extra $150 claiming that there is no such thing as a re-bookable flight. Travelstart not only provides poor service but also charges for services that the airlines do not honour. I am a frequent flier and often have to make bookings from various international locations and regularly require changes to travel plans both for myself and my colleagues. Travelstart is very good at taking my money but poor to respond to queries. I tried to cancel the ticket by sending an email and the agent just ignored my email request and did not respond to me at all. it has been more that 48 hours and I have not had any feedback.