Account query

Last year 2015 I closed my electricity account as I was moving out of the property that I was renting. After closing my municipality electricity account with an expectation of getting my deposit of R620 back, I got a surprise that I owe R63000. The account was not owing anything when I closed it. I complained about this to the officials and since then they have being taking me from piler to post. They claim that they did adjustments on my account which brought down the amount to R5000. This billing for this R5000 is estimated, like they estimated my electricity for the last 3years while I was renting. Apparently the meter for the property was changed, the last reading were never taken and they didn't update their system with the new meter number. When they send their billing it was still on an old meter number. I have being paying my electricity all these years and now I must pay for their mistakes. Write now as I'm sending this query the billing department is on strike and no one can help me with my query/complaint. At the moment I'm very desperate to end this issue because it has dragged long enough for them to resolve it.