TXU meter billing Internet, Internet

TXU came out almost a year ago, said there was an issue with our meter, had to hammer the lock off the meter, replaced it with a digital meter.  Turned around and charged use $1500 for 6 months of under billing and claimed that the lock was not there.  We monitored our usage and bills for 10 months, every month like clockwork.  Our normal bill was normally around $100 up to $150 a month, TXU came out and said they had an error reading and wanted to change meters again, (of course I walked out and caught the guy changing it, they didn't notify us) the very next month bill jumped to over $375 and we watch the meter and the changes and usage at with all power off is the same as it was with all power on with the first new meter.  TXU than said that they forgot to bill us, its computer generated bill, they show our usage is higher, me and my wife work 12 to 14 hour shifts are are only home to sleep.