I realise it can be spoofed and that multiple companies can use the same shortcode.  I have had one genuine link verification code from them (with a terse message "nnnn is your link verification code").  But the last one came when I was asleep.  If I knew which company (companies) use it then I could perhaps find out which account is being hacked.  I have looked at the list at vodafone but that stop is in teh 2000s.  Does anyone know who uses 3590