Drama and Alibi seem to have disappeared.

have they been moved or is it just a technical problem ?

They have not moved, still on the same frequency / satellite / beam.
But they did change the frequency parameters, so their owners (UKTV) could cram all their SD channels (inc Dave, Gold, Eden, Yesterday and +1´s), onto the one frequency (saves them money), and so by doing this the frequency is a tad weaker than it was before.
So to get it back it usually means a very small minute dish realignment, or lnb adjustment...but obviously it does depend where exactly you are and dish size.

Hi Guy,
I’m about 25 km S.E. of Valencia and I have a 1.9 mts. Dish, so I would hope to get them back again without affecting the other channels.
What do you think ?
Will it be very costly to get it adjusted ?

In that area, on that sized dish, you should be able to get them back again.
It should not affect other channels, but there are a few others (ITV1 HD, SD Discovery, some Sky HD channels like some Sky Movies and Fold HD and Nat Geo HD), that are on a weaker signal also, and sometimes it can be a compromise as to which to get, as the larger dish can get too much signal from neighbouring stronger satellites, that knock weaker signals out.

If you want me to add you to the joblist, drop me a PM here (or email via my website), and I shall see what I can do for you

It should only be a case of allowing the tuner to rescan the channels. Touching LNB or dish shouldn't be necessary. Try to to it during favourable weather conditions so you have a strong signal.

Actually the issue will be resolved with a small dish or LNB adjustment. Those group of channels are really sensitive to such a small movement in dish or LNB skew.
And if using a Sky (which the OP needs for Alibi) or Freesat box for the channels, then these receiver automatically update to any frequency changes anyway, so no need to "rescan" for the channels..

Go IPTV.

Why pay what is it now about £35/mth for the cheapest Sky sub without sport or movies when you can get absoulutely everything for maybe €180 a year, and a couple of weeks catchup to boot.

Not quite. £20-25/mth, and that is before they offer you their discounts..where you can usually get about 50% off for 18 months
For some people prefer direct from satellite especially if they only want the free channels, legal, or want full HD images (most IPTVs are barely 720, let alone 1080), and 5.1 digital audio (iptv only offer stereo), or have poor internet. But appreciate that it is the only alternative for some who live in weak signal areas. But for some, just cos it is cheaper, does not mean it is better....

Many thanks Guy, Will let you know as soon as I know my own plans. Normally go back to the UK this time of the year for Summer, but at present it’s all in the air.

Yes it must be as simple as that & we always used to bang the telly years ago and that worked sometimes.

The Guy has a reputation going back years giving very knowledgable (if not expert) info to any who should ask on the "forums" & as good a reputation from those he services as well.
Bonzo my advice is listen to the Guy.