Looking at the SDSs from each store, it appears The Chemistry Store does sell Croda's product, which contains Behentrimonium Methosulfate, Cetyl Alcohol, and Butylene Glycol. Chemistry Connection sells their own product, which is Behentrimonium Methosulfate and Cetearyl Alcohol. This is normally the INCI for BTMS-25, but unlike the 25% in that, this has up to 50% BTMS.
So if you created and perfected your recipe using the Chemistry Connection product, then it may not work quite the same with the Croda version. Butylene glycol is a humectant and might be a contributor to the softness, depending on your other liquid ingredients and possibly your humidity. And cetyl alcohol has a lower melting point than cetearyl alcohol, so could also change things.
I also notice while the Croda one lists 45-55% BTMS, the Chemistry Connection one says 30-50%. So with Chemistry Connection's version, you not only have the harder/higher melting-point cetearyl alcohol in there, but likely more by weight than the cetyl alcohol in the Croda one. So for example for every 10g Croda BTMS-50 you'd be getting ~4g cetyl alcohol, but maybe 6 or 7g cetearyl alcohol for every 10g of the Chemistry Connection product. This factor could definitely have added hardness to your bars. Hope this makes sense!
If you are stuck with the Chemistry Store product, you'll be able to formulate something that is hard with it, it will just take some adjusting for these factors. (I just realised I only addressed the hardness and not the oil leakage, but I think if you create a more solid structure, the oil leakage will likely be solved, too).
Sorry you had that experience with their customer service - that's completely unacceptable. I had something similar happen when I was trying to buy a pH meter from a supplier. A receptionist was so nasty to me out of the blue, and then claimed I'd tried to start a fight. I ended up sharing the email exchange with the owner and was issued a full apology. It's worth letting higher-ups know because sometimes they have no idea their customers are getting this treatment.