Problem fixed. Success at last!!!!!!!
Drive to the Vodaphone dealer (as advised) , a few suburbs away. He takes my SIM card out & puts it into another cell phoned. Deduces that the problem is not my phone, but Vodaphone's software. (Also tells me that next time I'm asked for my email address, that I absolutely do not own a computer! Got that, msolga? Good thinking!)
Get home. Ring Vodaphone tech support. Go over my problem in copious detail. Hold for minutes while tech help is consulted. Tech help deduces the problem is not with Vodaphone, but with Nokia (brand of my cell phone), possibly a virus.
Ring Nokia customer support. 5 times, before I'm actually able to get through (to possibly Sth Africa?) Explain the problem at length. A few times. Then get directions on how to proceed. Involving, toward the end, taking the SIM card & battery out for a bit, then putting them both back in. Going back to square #1 a number of times as communications go fuzzy. Finally, we do it! 8o + text messages (all the same) removed! Yay!
I ask: What caused this problem? Was it a virus? No, no, but it was all Vodaphone's doing, nothing to do with Nokia!
OK, OK, whatever .....