Hi and welcome,
If you have satellite dish of at least 1m, then you should be able to receive channel 4 and e4 on Sky channels 104 and 136.
As you say you have ALL other channels (inlcuding BBC2 on 102) then you should also be able to receive C4 on 104.
These channels have not changed frequencies for a few years.
If you used the Irish regional versions of C4 and E4, via other channels and with a Sky card, then these are still on the same frequency of 12480 v 27.5 2/3.
Also, note that channels on this frequency are susceptible to interferance from wireless devices (internet, wifi, DECT / cordless phones), and this interferance can cause these channels to drop out.
If you are unable to receive these channels then perhaps your dish is too small, out of alignment, or you need a new LNB or cabling.
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