The Atlantica Gardens apartment complex is part of the same hotel unit, although situated on the opposite side of the street to the (newly named) Atlantica Oasis.
Atlantica Gardens do have their own swimming pool, reception etc so at least you will be able to continue with the holiday unhindered.
However, all the main entertainment usually takes place in the main hotel - so looks like if the holiday goes ahead as planned, you could well be missing out on certain activities and if you have chosen or wanted to upgrade to a half board or better option, this may cause you further difficulties.