Hi @Ashish Agrawal and welcome to our forum! I'm sorry to read that there's some confusion regarding the purchase of your boosters, especially since the colleague you spoke initially hasn't informed you well. The boosters aren't free.  After you receive them they are in your possession and therefore they’re not free. You did get them at a discounted price, if you paid €79,- for two of them, as the regular price is €199,-.  If you don't want to pay for them, you have a 14-day return possibility for the boosters in which you can return them to a KPN store (don't forget to bring your invoice for the boosters) and you’ll get your money back. We cannot guarantee good Wi-Fi, as it's subjected to so many things in the environment that can disrupt the signal. However, we can support you in improving it by sending a mechanic or offering Wi-Fi boosters, the service that has been provided to you, although this isn't always free. It is also not mandatory to buy the boosters, but if they help to improve your Wi-Fi you have the option to buy them. 

I'm also sorry to read about your experience when contacting us after the visit from the mechanic. Know that we do value you as a customer, and I'm happy that you chose us to be your provider. There's nothing I can do to change our conditions regarding the Wi-Fi boosters, but if you’re not willing to pay for them you’re always able to return them. If you have a home with several floors it's very difficult to get a good Wi-Fi signal everywhere without Wi-Fi boosters, but of course you’re free to explore other options. Be it working more with internet cables throughout your home for example, or finding cheaper Wi-Fi boosters elsewhere. I hope I've been able to provide some clarity in this, but should you have any other questions, do let me know! 

I haven't heard back from you, so I hope my answer was helpful and you got the information you were looking for. Should you still have any questions, don't hesitate to ask them here!