Global Power Components interview questions

HR at this company is lacking. Had an initial phone interview just basic, who was I, what i was looking for and what the company did and the involvement i would have. Had a second interview in house where i was asked to do an assessment (solidworks) and take 4 tests based on mechanical comprehension, solidworks and auto cad. Sat down and talked with the HR guy and had a tour of the facility. He told me that he would let me know by the end of the week weather I had the job or not. End of week comes and had no word. He contacted me telling me that he would let me know on Monday. Monday rolls around and I don't hear form him, Tuesday the same and finally Wednesday he got back to me. had me come in for another interview with the owner. At that interview talked with the owner, generally about what my hobbies were and what my 5 year plan was, the meeting progressed to encompass what he would like for me to do to get myself up to pace with there product and system so I could better design there product. Then I meet with HR where they discussed my wage, benefits, vacation time exc. They told me to think about the job offer and get back to them after the weekend and decided weather I wanted to take the job. I called on Monday and accepted the job guy from HR was happy and saying how this is such a good fit and will be a great beginning to my career, I asked weather there was anything else they needed from me. He told me he would call me the next day with the information I needed to take the drug test that needed to be done before my start date. So great got the job, i'm excited to start working there the next week, told me current employer i was done and waited for the information i needed to progress forward. But non the less the next day i never heard from the HR. Another day goes by HR tells me they were busy and that he would follow up the next day. Two more days go by and I get an email saying that they will no longer be considering me for the position. WTF i was under the impression that i had accepted the job offer, we discussed my wage, benefits and start date. If this is any indication of how they do business I am happy I didn't end up wasting my time and effort with this company. very unprofessional.