I've never had any problems making myself understood when I've gone into one of Tunisiana's offices. You just need to make sure you ask them to let you know the important things, such as the PUK code in case you accidently lock the phone, and also the code to check your balance on screen (#100# then call if my memory serves me correctly). Bear in mind you can't go incognito there and your number must be shown, not hidden. Also make sure the language on your phone is set as 'English', as if it is 'Automatic' it will come up in French. You can top up easily at any of the places showing Tunisiana (or Tunitel if that is the company you choose) by putting in the number on the receipt you will be given for your dinars. If your French is good you can take advantage of all the other wonderful things you can do but unfortunately mine is abysmal so I don't bother with them. It certainly saved me a lot of money last time when my daughter-in-law's dad had a massive heart attack the day I went out and I needed to keep in touch.

going to the office is fine. I've been to the tunisiana office in sousse on several occasions. I'll tell you something, I wouldn't mind working in an office with a background view of boujafaar. It's if you can't get there, you're not local and need to call customer services. I needed to do this to set up mms, internet and find out where my missing credit had gone. During those times my tunisian friends were like blessings in disguise. When you telephone customer services you better be able to speak arabic or french otherwise chances are they will not understand you.
Also tunisian mobile phone costs are not that cheap. Obviously cheaper than using your UK phone out there but we in europe have much better phone packages and pricing plans. When out there I easily spend about £20 per week on phone cards and that's just talking to tunisian friends and sending texts. Pay as you go for me out there is more expensive than my call package over here. It's about time they made contracts more accessible with inclusive minutes, texts, etc.

I think it's a case of 'horses for courses' and one size obviously doesn't fit all. I only use my phone to phone and text and don't bother with internet or e-mail so it has worked out very well for me. I know you only get customer services in Arabic or French but I'm sure if you didn't have Tunisian friends you would always find someone in the hotel to help if needed. I certainly agree with you regarding Tunisiana's office in Boujafaar.