Questions about web automation development

[Jime]

I want to develop an automation software for web pages, he can automatically log in to check the inventory of his own account, and automatically complete the purchase and check the balance in the store through Subid for each account. But I don't know where to find the right developer. I've tried several developers and they can't solve this problem. Do you have any good suggestions, doctor, what language should I find someone who is good at writing this website? Because I have failed many times.