Byjus - Tablet replacement

I subscribed for my two children from January ****. One for my son for *th & **th STD and another for my daughter for *th to **th. This April **** due to covid, as the schools were doing online classes I tried to install Google meet and classroom in the tablet it misbehaved and we had to reset the tablet * to * times due to which the byjus app got erased. When the mentor of byjus asked my kid to login to byjus app we told them the above issue. They sent us a new *** gb sd card as replacement for the erased sd card but it was not accepted/ supported by the tablet as it can support only upto **gb sd card and having just *gb ram. We informed about the issue and the mentor asked us to send the tablet to them and they will send the replacement. This thing was going on since April **** till **th July ****. I sent the tablet to them on **th July **** and was received by byjus on ** th July. On **th July the mentor confirmed about receipt of tablet and assured me of sending the tablet within * days. But today on **th August **** the mentor told they will not give the replacement as it was damaged ,which we were not aware of , and since it was used way back in March **** they will not provide the replacement of tablet as it was not used till it was sent back to them. This issue was going on from April **** and now they give excuse as it should have been used till last week. Please help me with the refund.