IS backbone question

[Slush-puppy]

I use Afrihost as a isp. i started with their uncapped then moved back to capped due to high latencys during the day time after averaging 22 gigs on uncapped a month.So then i got a nexuss account from one of my friends wich is on the saix backbone and used it to test if it was my line or isp, and with the nexuss account latencys low whole time.Then i jumped to the conclusion its Afrihost but before changing isp i tried axess account wich is also Is based like afrihost of one of my friend and also high latencys during business hours.

latencys of 80 ms and up with the Is based acounts and with the saix nothing above 25 ms

Please correct me if i am wrong some where.

Could this be a backbone problem only me experiencing these issues?