GETTING MY TROPICAL FISH SHOP LONDON TO WORK

Cost of £four,500 to put in sleeper pond promising long term maintenance but are not able to get them to come back,lost four x 2ft fish that put in Keeping tank,should have been there for just one week but it had been four, are unable to suggest this corporationAm i able to continue to keep two Crowntail fighter fish in a similar tank? It’s freq