Harp Well and Pump Service Inc

My electrician and I installed the new pump.  The pump still didn't work.  I just purchased a $450 pump I was told I needed by Ed at HARP.  I had left my old pump with HARP the previous day.  So we took the starter again to HARP and Ed re-checked the starter.  Guess what, the starter was bad so Ed eagerly GIVES ME A NEW STARTER--I didn't have to pay for the starter.  I picked up my old pump.
We installed the starter and the new pump still didn't work.  We re-installed the old pump and it still didn't work.  I called HARP to have them come out to look at the system.  The service people were on time and excellent.  They were there for just less than an hour and had found that my electrician had crossed the two hot wires.  I was told that  it was a common mistake but that the electric lines had to run directly to the pump and even though the lines both carried the necessary power, they had been switched at the outside emergency shut off switch.  I asked them how much I owed them and they didn't know.  I was told that I might not get charged for their service but that they didn't have a bill for me. 
A few days later, I had a bill for $160.95.  I immediately went to HARP and paid the full amount in cash and asked if there was anything they could do about the new $450 pump that I didn't need. I was told flat out no, I had it installed and they couldn't take it back.  It was in the water less than 2 min. I didn't say a word.
On 7/17/12 we received 4 calls from HARP saying I hadn't paid the service invoice  for $160.95:  2 calls to my home, 2 calls to my cell which I answered both times and told Mary that I had paid in cash.   I sent HARP a copy of the "Paid in Full" receipt,  I received from them on 5/21/12 along with a section of a book about successful businesses that had started in Kansas, that was, in part; written about my electrician, because Mary started to talk negatively about my electrician--I could overhear Ed in the background feeding her information.  Mary was not aware of any of the issues I had and had not been involved in my situation until the billing.  I tried calling HARP on 7/17/12 to let them know my wife had found the receipt--it was after hours, no answering machine. 
Not only did I receive extremely poor service by the office sales people, by incorrectly diagnosing my starter, I now own a $450 new pump with the warranty expiring, but their bookkeeping is so poor that they lost $160, or someone has problem keeping the cash drawer accurately.  How does a business lose $160?  I hope their service people go to work for another well service, because I won't be referring HARP to anyone.  Had the original diagnosis of the starter, by a company that is extremely familiar with these starters been correct, I wouldn't have wasted $450 and I wouldn't have been harrassed for another $160 for something I had already paid.
Some of you might ask, why did I pay in cash for the service call?  I didn't want my wife to see that we spent an extra $450 for a new pump that wasn't the problem.  She would have already had an attorney involved.