It appears that Caja Canarias bank are carrying out a "restructuring" - meaning temporary closure of certain of their branches - Los Gigantes office being one of the effected branches. The bank will open only on a Tuesday and Thursday from 1st August >31st August - other days of the week CC suggest you visit the nearest open bank which is in Pto Santiago.. I am unsure as to their opening hours from Sept onwards but I feel it is likely that they might not be open 5 days a week from hereonin.
Given that usually only one cashier is on duty and has to handle money in/out and deal with queries from customers heaven only knows what the queue will be like when they open only 2 days a week as even when they opened 5 days a week you more often than not had a long wait to be served
Indeed, if you only came for a weeks holiday you could spend most of it queueing in CC bank !!!