Notary help - sale of apartment- please advise me :(

Hi all, can someone please help me out here.

I am seeking some advice as I am at the end of my tether with frustration.

We own an apartment in Gozo and have been trying to sell it for years now, we had a sale fall through due to the COVID situation, we are using a private agent, basically a person we know that has done al the leg work to find a buyer, and we have luckily found a new cash buyer from Malta, they have agreed to use the same notary as all the searches have been done by them, we had a zoom meeting with them and the Notary and a new pre contract we signed using this method, now we have a couple of issues, the first being that the Notary hardly ever responds to emails and the deadline of the pre contract is drawing near (29th of Dec) as we have been bounced from pillar to post with architects looking at floor plans of the 5th floor instead of the 4th floor, this is still an issue!
As Xmas draws near and the expiration of the pre contract we are finding it difficult to pin down the Notary on a date for us to be in Malta to sign the final sale, flights are now £400 each for me and my wife and are few and far with limited service, plus we have to get a COVID test done that only lasts 72 hrs in order to fly, all getting very tight time wise and expensive!
The notary has advised us that we can get one of her colleagues to have power or attorney and sign the final sale for us eliminating the need for us to be in Malta, we have a bank account in Gozo so that's not a problem, my issue is how feasible is this and what is our legal position, not knowing Maltese law.... can the Notary be trusted to do this? what is stopping them just pocketing the money from the sale, I do not mean to cast a net of distrust of the legal professionals of Malta but we have had such a negative experience with this particular notary I am very suspicious of signing over power of attorney to a colleague.
Can anyone help with advice, has anyone experienced any of this in the past or have any knowledge as to the legal obligations of the Notary?

Any feedback would be gratefully received, please stay safe and have a great Xmas to all of you.