Refusing toilet access

I do usually travel with Intercape and although they were never a great service I found it, it is what it is. But on Friday I traveled from Bloemfontein to Johannesburg via Potchefstroom and the first comfort stop was in Klerksdorp, 4.5 hours into the trip they only stopped. If you complain about the lack of comfort stops they say but there is an onboard toilet, yes one that smells so bad, you can smell it from your seat, who would even attempt to use that? The customer service told me that I must plan around the comfort stops, going to the bathroom BEFORE departure, I must be considerate towards the other passengers and that I can book a ticket on one of their other busses. So meaning it is my responsibility and I must carry the financial burden because they expect their passengers to hold their bladders for 5 hours plus? I couldn't cancel the return ticket because then there would've been a cancellation fee as it so outside the free cancellation window, so on the return trip I asked the driver 15 minutes before departure if I could go to the bathroom and I was denied. So if I must go before departure but I am not allowed to go 15 minutes in advance when am I actually allowed to go to the bathroom?