R2400 to R7800 because "only the office can provide a quote" - after the work is done

I contacted this bunch to assist in getting my DSTV cable re-connected (a 10 minute job), that was it. They convinced me we needed a new Extender box, and was quoted R2400. I expected a bill round there, plus some labour. A R7800 bill arrived instead!!!! Suddenly there was a Lnb optic, lightning protector surge x 2 (which is BS, those were already there), a cable fee?, and R1800 installation fee. What a joke. I seriously urge you to obtain a written quote. Preferably from a more scrupulous business.