Short code texts not coming through

Hi, I am new to this community. I am writing in desperation! Until last Thursday my Interactive Investor (ii) app worked fine - the six digit code came through ok for me to log on to the app. I have been using the app for years. Now, suddenly for some reason, I no longer receive the text so cannot log on. ii are baffled by it as well.

Not only that, I have just discovered can't receive Smarty texts either!!!

Any advice, please?