Loud Humming Noise after new blower fan and motor installed in Lennox unit

I have a G50UH Lennox and the blower fan got wobbly and started thumping and screeching at the end of cycles, so I had a new blower fan, squirrel cage and fan motor installed on Monday. I told the tech it sounded very loud to me and he shrugged and said at least it's not thumping and bumping like it was, and left. I thought maybe it was my imagination, but there's a loud humming sound like a motor hum or a washing machine on high spin cycle that fills the house every time the fan kicks on now. I had a couple neighbors come over to hear it last night and they said no, not right, call them back. I'm a single woman who knows very little about HVAC, and since the tech blew me off when I said it was too loud when he was here, I'm worried they will either 1) Tell me there's nothing to be done or 2) Try to charge more $$ to fix it. I can't call them until tomorrow since this is a holiday, but ... does anyone have any thoughts on what could be causing this after having a new blower fan and motor installed? Is it a bad motor? Does it need to be adjusted, maybe lower the fan speed? Should this cost me any more to have this fixed by the same company? I've already paid nearly $700 for what they did Monday. Thanks.