GregM1

1. We must install geyserwise and change form 4kW to 2kW element - this is spot on. 
2. He needs to adjust setting so that battery does not discharge so low, but accesses ESKOM to keep charged when it needs to. All done at additional cost and the battery now never drops below 90%. Draws on Eskom fortunately Eskom has also played along with no or less load shedding. - not sure why your installer charged you additional here, this should have been his stance from the get go. Your battery has a SOC and discharge limit, once you hit the limit that equals 1 cycle (in some cases with certain batteries the cycles differ) cycling your battery more often reduces battery life. But at your rate and the adjusts you should be fine for another 10 years at least. 
My question here is what should that setting be to prevent total drain. I believe 90% is an overkill and maybe should be 40 or 50% . Only wife and myself at home. We are in our 60's and daily units used before installation was between 6.5 and 11.5 average 9.1. We have a 5kVA battery - this should be set on the inverter as per the battery manuals, should not go lower than 20% I would suggest. 
A further question is the geyser temperature according to the geyserwise display gets to 55, and I am finding 40s is comfortable enough to shower. My wife however is complaining that it is not hot enough when she wants to do dishes and has taken to boiling a kettle of water to top up temperature fordishwashing . Some advise please from the longer term system users. - comments by the the other  forum members is spot on 55 degrees is a good temperature, also look into installing a geyser blanket to keep the water warmer for longer.