FNB continues with long random SMS numbers

Dear FNB I'm writing for the 4th or 5th time in about as many years to complain about your use of long random SMS number to communicate with your clients, this time over the delivery of my new debit card, with each communication coming from a different number. Why is it so hard to see the security hazard in this?! A long random number means I can't be sure it comes from FNB and it means you can be ****fed. It is also a typical way for spammers to hide their caller ID and prevent being blocked. The fact that I must explain this to my bank does not make for peace of mind about your ability to deal with security generally.