It happened to me once - turns out there were two vipers mating among the tree branches that directly obscured the satellite dish in spring/summer. Fired a few shotgun shells in their direction. It took out both vipers and plenty of branches. Didn't have any problems with DStv reception until the next spring/summer. Didn't find any vipers. Didn't know what the missing link was, so I gave up and migrated.
Which channels are you experiencing these issues on?
DSTV are doing lots of moves of channels from some transponders to others, which will affect marginal installations in some cases.
The usual causes are:
1. Cables damaged by UV breaking down the outer insulation, followed by water ingress.
2. Bad connectors on the LNB side of cables.
3. Antenna badly aligned and marginal, which then affects performance on some transponders more than others.
4. Trees growing and blocking the signal.