Hi everyone, this is my first ever post so please be nice

I used a stud dog for my bitch and this was done via artificial insemination. I was there when the sperm was collected from the stud and watched the insemination process, although the stud owner used a different method to the iv tube type...the owner said it was a new method and she was first in uk to use it...it looked like a human vibrator which was inserted in my bitch and pumped up to resemble the males swollen penis and she attached the syringe to this proceeded to insert the sperm. This was done on two occasions 48 hours apart. I paid the £400 at the first AI as this is what the breeder stated.
Sadly after having a ultrasound my bitch did not have any pups. I notified the breeder and she said she was gutted. I have stayed in contact with the breeder and last week we thought my bitch was again coming into season so i contacted the stud owner letting her know but I received a text message back stating that the stud was put to sleep and that as she owed me a mating that i could use a friends dog instead. I am not happy with this as the friends dog is not the colour i wanted to mate my bitch with and not to the same standard to which i wanted for a mating.
Can anyone advise where i stand on this can i refuse the offer of the friends stud use?
Can i insist on my money back or at least part of it, seeing as the stud I originally used and wanted has been put to sleep?
It just seems a bit strange to me as he seemed very very healthy (i know looks can deceive), they insisted he was very very healthy. And the fact that nothing was mentioned to me sooner, seeing as we chatted often via text!
I did not have a written contract but it was a verbal with witnesses present and i have quiet a bit in text which states use of the stud and recently stating i am owed a mating seeing as the last did not take. The stud owner even went as far as saying to me verbally on the phone that she guaranteed she would take next time.
Any help appreciated