Telkom DNS server timeouts

I'm on 8ta 3G in Cape Town and over the last few weeks access to the default name servers has become progressively worse to the point where I now am using Google's public DNS servers instead. Queries just time out most of the time to Telkom's name servers. At the time of posting they are currently available, but it's been a roller coaster for a while now

I've tried:

196.43.34.190 *8ta default 1
196.43.46.190 *8ta default 2


and all the ones at http://www.saix.net/cgi-bin/saix_dns.pl

Does anyone else have this problem, or know of a possible cause?